Abstract

Time-resolved photoluminescence measurements on polycrystalline (CIGS) thin films corresponding to high-efficiency solar cells indicate recombination lifetimes as long as , far exceeding previous measurements for this material. The lifetime decreases by two orders of magnitude when exposed to air. Charge separation effects can be observed on devices in low-intensity conditions. The ZnO layer forms a robust junction critical for charge separation, whereas the CdS layer alone forms a much weaker junction. Recombination at the CIGS/CdS interface is negligible. The results significantly adjust the previous picture of recombination in CIGS solar cells.